Burn Baby Burn! For the Longleaf Pines

The recent forest fires have been wreaking havoc across California since early October. In fact, destructive wildfires are a frequent occurrence in the dry, western state. Such fires are generally bad news as they cause destruction of property and affect air quality. However, are they always bad? Interestingly, the answer is no.

Wildfires can be an intricate part of a forest’s natural cycle, and may even help its survival. One such example lies in front of our eyes in the state of North Carolina, where the longleaf pine finds its home.

Longleaf pine forests across the Southeastern United States are one of the most diverse environmental systems in North America. At one point in time, they covered about ninety million acres of land which, unfortunately, has decreased to only about three million acres. Human development and exclusion of fires by human effort are largely responsible for this decline. Longleaf pines are adapted to fire cycles; preventing fires actually hurts the health of the forest. Native Americans realized this correlation and rarely intervened whenever lightning induced fires, which were common events in the Sandhills region, a major home of the longleaf pines located in North Carolina, South Carolina, and Georgia.When the early European settlers came over, they realized the potential of pine resin in shipbuilding. Very soon, North Carolina’s pine forests became a supply line of naval stores for the UK’s Royal Navy. These early settlers however still continued to burn fires like the natives and thereby contributed to the health of the ecosystem. It was only with growth in plantation forestry came an urge to desperately eliminate fires.

Photo taken by Manisit Das

Longleaf pines, in their sparkling green glory. Weymouth Woods, Southern Pines, NC

The Sandhills region is home to about a thousand different plant species, the dominant species being the longleaf pines. With their long needles, the pines produce a bright, shiny green canopy growing atop massively tall trunks.Additionally, the forests support a wide variety of animals amounting to 160 different species of birds, including the endangered red-cockaded woodpeckers, a large number of salamanders, toads, frogs, the hognose snakes, and fox squirrels, and many other species.  In the twentieth century, firefighting prevented the regeneration of longleaf pines, providing non-fire resistant species a competitive edge. That, coupled with increasing human settlement, reduced longleaf pine forest covers. In 1963, the remnants of the natural home of the longleaf pines were brought under the state parks system when Weymouth Woods was established. Since then, simulated prescribed fires are used systematically as a conservation tool to restore and maintain the longleaf pines.

An unexpected player in the conservation effort is the US military. The military base Fort Bragg, bordering the towns of Fayetteville and Southern Pines in North Carolina, is home to some of the world’s largest biodiversity reserves. The army recognizes that maintenance of the natural environment is crucial. The live ammunition exercises conducted by the military in this base already help protect many of the plant species, some of which are exclusive to Fort Bragg. If these rare plants are not preserved, most of the world’s populations of these species will be lost. Understanding the need of the hour, the military installation is taking one further step: in collaboration with the North Carolina Botanical Garden, they have launched an effort to reintroduce some of the plant species at risk into the Sandhills ecosystem.

Weymouth Woods Sandhills Nature Preserve, a North Carolina State Park in the Moore County around Fort Bragg, offers a great snapshot of the magnificent pine forests that once covered the southeastern United States. During my visit, I was surprised by the wide variety of wildlife I encountered within a short period along the sandy trails. This included a large number of dragonflies, skinks, a moccasin, and not to mention the diversity of plants that coexist in the Sandhills pine forests. If you are intrigued by the unique nature and ecology of the longleaf pines, their role in North Carolina’s history, or simply take pride in being a ‘Tar Heel’, I definitely recommend visiting this place. You will not be disappointed in this treasure trove of nature.

Peer edited by Caitlyn Molloy.

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How’s that Nanoparticle Biocorona treating you??

No, sorry, it’s not the latest variety of Corona beer. Rather, it is a new exciting advance in understanding nanoparticle toxicity!


 ©2006 David Hawxhurst, Woodrow Wilson International Center for Scholars

Nanoparticles are found in lots of consumer products!

Nanoparticles are any really really small particles in the nanometer range (1-100 nanometers). For size comparison, the thickness of normal hair is 80,000 nanometers. Because they have different chemical and physical properties compared to larger particles, nanoparticles are already being used in numerous capacities. They are used to produce lightweight but strong materials for use in airplanes, in clothes to kill bacteria, in food packaging to promote shelf life, and in sunblock to improve UV protection. Much research is ongoing to include nanomaterials in medicine, such as to treat cancer and to improve medical imaging.

Though nanoparticles are becoming widely used in consumer products and there is increasing development of nanomedicine, our understanding of how nanoparticle exposure affects human health is struggling to keep up. Thus far, researchers thought that nanoparticle toxicity was dependent primarily on physical or chemical properties, like composition (silver vs. iron) or size. However, recent findings indicate that it might not be that simple.

The Biocorona

When nanoparticles come into contact with biological materials (for instance, the blood), proteins and other molecules are naturally attracted to its surface and begin to form layers around the nanoparticle. This biological coating is known as a biocorona. Thus, when the body is exposed to nanoparticles, it is likely encountering nanoparticles with a specific biocorona that has formed on it, not just the nanoparticle itself. Different biocoronas on the same type of nanoparticle can affect not only the particle’s chemical properties but also how it’s distributed throughout the body, how it’s eliminated from the body, and how the body reacts to it.

Dr. Jonathan Shannahan at Purdue University is one of many researchers trying to better understand how nanoparticles interact with the human body and the role of the biocorona in modifying toxicity.

Nanoparticle Meets Heart Disease

Recently, Dr. Shannahan’s team published a paper on how cardiovascular disease states can affect iron nanoparticle biocoronas and toxicity. Iron nanoparticles are being developed for use in medical imaging and cancer drug delivery, so it is important to better understand their potential toxic side effects in humans. Many of the current iron nanoparticle toxicity studies have been designed to represent how a healthy individual would react. However, 1 in 4 people in America die from cardiovascular disease each year and 31% of Americans have high levels of cholesterol in their blood, a high risk factor for cardiovascular disease. The toxicity studies we have now do not capture the effects of nanoparticles in a significant portion of the population, people with or at high risk of developing heart disease. These people may also use iron nanoparticle therapies and diagnostic tools so it is essential to study how people with these underlying disease states would react.

Courtesy of Dr. Jonathan Shannahan

Iron nanoparticles form different biocoronas when incubated with different kinds of serum (normal vs. hyperlipidemic) which generate different responses by the body.

To simulate normal and heart disease conditions in their experiment, Shannahan’s team incubated iron nanoparticles with blood serum from normal rats and rats with high blood levels of cholesterols (think LDL) and lipids, termed hyperlipidemic serum. They found that the nanoparticle biocorona changed when incubated in hyperlipidemic serum and that nanoparticles with a hyperlipidemic biocorona stimulated more of an immune response in cells that line the arteries! An increased immune response facilitates the formation of plaques in the arteries, which eventually could cause blockage of blood flow to the heart, leading to heart attacks.

Shannahan’s findings suggest that individuals with high blood cholesterol and/or heart disease may be more susceptible to the toxic effects of iron nanoparticles, i.e. they could have a worse reaction to iron nanoparticles than healthy individuals, and that this toxicity is driven by a change in the nanoparticle’s biocorona.

“King me.” – Nanoparticlenanoparticle

The discovery of this biological “crown” on nanoparticles and its ability to affect toxicity adds another piece to the complex puzzle of how to evaluate nanoparticle toxicity in humans. Such studies will only become more important as nanoparticles become more widely used in consumer products and, potentially, in modern medicine. Genetics, epigenetics, nutrition, environmental exposures, and now biocoronas will all play into the important quest to understand the toxicity of nanoparticles among the general population as well as for each individual.

Peer edited by Aminah Wali.

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Toad-ally Accurate Predictions?

Today, groundhogs tell us if there will be six more weeks of winter or an early spring. Soon, puppies will be unleashed to help predict the Super Bowl winner. But have you ever considered looking to toads in order to forecast earthquakes?

Animals and Earthquakes

For centuries, there have been reports of animals acting strangely before an earthquake. From ancient Greece to the modern day Bay Area, people have observed rats, snakes, and dogs leaving their normal habitats for safe shelter in the days leading up to an earthquake. Currently, seismologists do not have a way to accurately predict earthquakes, so these animals may provide some clues. One Japanese doctor claimed that earthquakes could be predicted by unusual dog behavior, like an increase in barking or biting. Despite continued research efforts in Japan and China, countries often hit by devastating earthquakes, no consistent relationship between animal behavior and earthquakes has been seen.

Toad-ally New Connection


The humble toad, Bufo bufo, holds some promise for detecting pre-seismic changes and alerting us of imminent earthquakes.

The observation of odd toad behavior before an earthquake was published in the Journal of Zoology in 2010. Rachel Grant of Open University was studying the how the lunar cycle impacted toad behavior and reproduction in L’Aquilla, Italy when one day, she noticed there were suddenly no toads at the breeding site. Such behavior was extremely odd in the middle of mating season since toads do not leave until breeding is completed. A 6.3 magnitude earthquake occurred in the area days later and the toads started returning the day after the earthquake.

Grant was curious about what cues the toads were responding to when they departed the breeding site. She found reports that there had been changes in the ionosphere, which is the upper layer of Earth’s atmosphere, leading up to the earthquake. These changes are common before earthquakes and lead to a lot of gases being released into the atmosphere, which could change the water chemistry of the toad habitat. Toads and other amphibians are very sensitive to such changes, so this disruption may explain their sudden departure.

While intriguing, more work will need to be done to take this study from a well-documented anecdote to a reliable method for predicting earthquakes. A similar mass migration of toads was seen in 2008 before a large earthquake in China, but all of these results will have to be replicated at these site and others, which will be difficult due to how rare and unpredictable earthquakes are. But in the meantime, if you see a mass exodus of toads, it might not be a bad idea to follow them.

Peer edited by Madelyn Huang.

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Does this chemical make me look fat?: Secret suspects in the obesity epidemic

Over a third of the adult population in America is obese (Body Mass Index (BMI) ≥ 30) and an additional 40% are classified as overweight (BMI 25-30). Within the past ten years, this rate has increased significantly. Obesity increases risk of cardiovascular disease, type 2 diabetes, and some cancers. According to some estimates, the medical costs of an obese person is $1429 more than a person of normal weight. While exercise and diet are very important factors that regulate a person’s weight/obesity, there may be something else interfering with the body’s natural weight regulating processes: obesogens.

Adapted from Wikimedia (https://commons.wikimedia.org/wiki/File:USA_Obesity_1998.svg and https://en.wikipedia.org/wiki/Obesity_in_the_United_States#/media/File:USA_Obesity_2011.svg)

Obesity is increasing in the USA and worldwide. Map generated from data from the US Center for Disease Control and Prevention.

Coined in 2006, the term “obesogens” refer to chemicals that may predispose an individual to gaining weight. Scientists have observed that numerous chemicals caused weight gain and obesity in animal studies, including tributyltin (pesticide), BPA (in plastics), phthalates (in plastics), PBDEs (flame retardants), and fructose (in diet). Persistent exposures to these chemicals in adult and particularly in early life, even in small doses, can have lifelong implications.

Since the field of obesogens is relatively new, how these chemicals affect obesity is still being discovered. Some chemicals act by reprogramming stem cells to differentiate into fat cells, thus increasing the number of fat cells in an individual. This number contributes to determination of the metabolic set point of an individual, or the set weight that the body is programmed to maintain.  Fat cells also secrete hormonal signals that affect metabolic regulation throughout the body, such as leptin. These hormonal signals also influence neurological signals in the brain that control feeding and satiety. In addition to increasing the number of fat cells, obesogens may also target metabolism and the brain directly.

Some obesogens have transgenerational effects, where an effect of an exposure is seen in a generation that has had no direct exposure to the chemical.  Researchers are finding that when animals are exposed to these chemicals, effects can be seen in their offspring and even the third generation!  In other words, the effects of exposure to these obesogens may be heritable. These fattening signals could be passed on through genes or through epigenetic markers.

If the pregnant mother (zeroth generation, F0) is exposed, then the fetus (1st generation, F1) and the fetus’ germline (future baby in the baby of the exposed mother, 2nd generation, F2) are also exposed. Thus, the chemical itself could be causing obesity in these generations. However, the third generation (F3) will not have had any exposure but the effects of some obesogens are still observed!

Obesity is a growing public health problem with serious health consequences. Increasing scientific evidence supports the idea that obesogens may be predisposing people to becoming obese. The transgenerational effects of obesogens highlights the importance and urgency of this kind of research, in order to protect not only the pregnant mother and her child, but also the third generation and beyond. Continued research in this field, mostly funded through the National Institute of Environmental Health Sciences, will support the establishment of policies that would regulate production and exposure to these chemicals. In the meantime, while obesogens might play their part, we also need to play ours. We should strive to maintain healthy lifestyles and eating habits, which are well-known methods to improve health.

Peer edited by Joanna Warren

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Milking Cellular Agriculture for a More Sustainable World

Could you live in a world without beer? For at least 2 billion people, the answer would be a resounding “NO!” Many alcohols, like beer, exist because of a microorganism known as yeast, which uses fermentation of sugars to make breads rise and create alcoholic beverages. Now, yeast are poised to transform the way we think about other foods, thanks to scientists working in the innovative new field of “cellular agriculture” (coined by Isha Datar, CEO of New Harvest).

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Kites Reveal Clues about Coastal Change

Duke undergraduate student Amber Oliver shows off the 3D printed rig which supports and stabilizes the camera.

This summer, an afternoon spent flying kites at the beach will be just another day at work for some researchers at the University of North Carolina at Chapel Hill.

Now that classes are out of session, Elsemarie deVries and Evan Goldstein don their sandals and sunscreen haul kites and cameras to the Outer Banks in the name of science. They are coastal geologists who study how beach grass and sand dunes affect each other.

These researchers are part of a “21st-century renaissance” of scientists who use kites to collect geographic information. A camera cradled beneath a kite snaps a collection of what Goldstein calls “higglety-pigglety images” from all over the beach. Once they get back to the lab, the team uses software to stitch these pictures together into a 3D map. With enough data, they hope to understand how dunes grow.

To attach real dimensions to their maps, the researchers roam around on the beach with a GPS unit, noting the coordinates of specific locations. In a pinch, anything can be a ground control point – on one memorable day, dog-poo bags marked the GPS locations (although deVries is quick to point out that the baggies contained only sand – not feces).

Although many people find the beach a relaxing place, Goldstein says that some of these trips to the coast have actually been “pretty stressful.” Particularly windy weather can sour a field excursion since strong wind can send the kite into a nosedive. To solve this problem, Goldstein dove headfirst into the physics of kite flying literature (yes, that exists), and the team picked up a more stable kite with a keel.

Evan Goldstein snaps a selfie with one of the airborne cameras. Both images courtesy of Evan Goldstein.

Now that they know how to capture these bird’s eye images and turn them into topographic maps, Goldstein is setting his sights on “capturing time series – going back to the same site repeatedly over and over again.” They hope that building a series of 3D maps will show them how plants and dunes change together.

Taking pictures with kites instead of, say, drones, which are increasingly used for aerial photography, may seem delightfully quirky and old-fashioned, but cost and legality make kites an appealing option. Even though the kind of kites able to support a camera cost a little more than tuppence for paper and string, they can still be less pricy than drones. Goldstein also points to “the regulatory advantage” as a key reason that kites will be keeping this research aloft in the upcoming months.

Author’s note: Although I am not involved in the kite mapping project, I am a MS student in the same lab as Dr. Evan Goldstein and PhD candidate Elsemarie deVries, under the direction of principal investigator Dr. Laura Moore. Dr. Kenneth Ells of UNC-Wilmington is an additional collaborator on this project.


Edited by Suzannah Isgett

The Yellow Blanket of Spring

Image of pine tree pollen in flight. Photo courtesy of <a href="http://amycampion.com/what-happens-when-you-tickle-a-pine-tree-in-spring/">Amy Campion</a>

Image of pine tree pollen in flight. Photo courtesy of Amy Campion.

For a few weeks every spring, Chapel Hill and Carrboro are covered in a yellow blanket of pine tree pollen and everything’s a mess. Birches, oaks, pines, and more get the signal to “spread the love” and distribute their genetic material all over the place, irritating our eyes and noses. But how do plants know when it’s time to release their pollen? You may have learned in elementary school that warm weather activates the flowering gene in plants. While temperature plays a role, it is not the only trigger. Remember that random week of warm weather we had at the end of February? Why didn’t the pine trees start distributing their pollen then?
Spring ushers in longer days along with warmer weather. The amount of daylight a hemisphere receives changes as the Earth orbits the sun. In the winter, our hemisphere (the northern one) tilts away from the sun, reducing the amount of sunlit hours in the day. In the summer, our hemisphere tilts toward the sun. This means that between the winter and summer solstices, as the Northern Hemisphere transitions from tilting away from the sun to tilting towards it, the amount of daylight increases.
The changing length of day throughout the year being a consistent phenomenon, plants have developed a mechanism that uses the amount of daylight as an indicator to flower. The photoreceptors that allow sunlight to enter and initiate photosynthesis, the process by which plants transform light into energy, also activate proteins. Thus more daylight means more protein. And once enough protein builds up, the plant gets the signal to flower.
Imagine the protein as sand in an hour glass. When the sun rises, you flip the hourglass and sand begins to trickle down. After the sun sets, you flip the hourglass back over and the sand that built up during the day pours out. During the winter, all the sand that builds up during the day will empty at night because the nights last longer than the days. As you approach spring, each day the sun is up a little longer, meaning a little more sand can accumulate. At a certain point, your hourglass will build up enough sand during the day that some will still remain at the end of night. Once the protein reaches this threshold, the flowering gene in plants can activate.
But what if the days have lengthened and it is still cold out? If it’s too cold there won’t be bugs or other animals around to help spread the pollen. Thus, plants also rely on the temperature as a secondary indicator. This is where things have recently started to get messy. Global climate change has reduced the number of lingering cold days in the transition from winter to spring. As a result, scientists have noticed that plants are flowering earlier, and allergy season is starting earlier and lasting longer than in previous decades. So, if you’ve noticed your nose itching sooner and you can’t seem to shake your sniffles, you’re not crazy.

Fortunately, there are steps you can take to reduce your allergy symptoms while you wait for those cleansing April showers. Rain will reduce the amount of airborne pollen and wash away the pollen that blankets your car, creating little yellow rivers that will whisk away the pine trees’ genetic material. Then Chapel Hill will once again be Carolina Blue—until next year.

Peer edited by Rachel Haake & David Seamans

Global climate change: How does it happen, and is there hope?

The coming of the New Year often brings about feelings of nostalgia as we reminisce about the previous calendar year. Looking back at 2015, we as humans have quite a bit to be proud of: the granting of women’s voting rights in Saudi Arabia, the development of a new highly effective drug for the prevention of HIV infection, and of course, the new Star Wars film. However, arguably one of the most significant accomplishments of 2015 was the Paris Agreement – the first-ever universal, legally-binding global climate deal.

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Traveling trees: how fast can they migrate to track climate change?

Most readers are probably familiar with some of the implications of climate change: sea level rise; more frequent extreme weather events; habitat loss for arctic species. Other implications are equally important to understand and reach into many realms of ecology (as well as other disciplines), but are not popular topics covered in the media. Continue reading